Electrolyte membrane

ABSTRACT

Systems and methods of providing an electrolyte membrane for metal batteries are described. According to aspects of the disclosure, a method includes preparing a mixture including an electrolyte portion and a matrix precursor portion, forming an electrolyte membrane by initiating polymerization of the gel-forming precursor and the gel-forming initiator to thereby form a polymer matrix, and disposing the electrolyte membrane between an anode and a cathode. The matrix precursor portion includes a gel-forming precursor and a gel-forming initiator. The electrolyte portion is disposed substantially throughout the polymer matrix.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/681,142, filed Aug. 18, 2017.

INTRODUCTION

The disclosure relates to the field of electrolytes for metal batteriesand, more specifically, to systems and methods of providing self-healinggel-type electrolyte composites for metal batteries.

The lithium class of batteries, such as lithium-metal, lithium-ion, orlithium-sulfur batteries, has gained popularity for various reasons,including a relatively high energy density, a general nonappearance ofany memory effect when compared to other kinds of rechargeablebatteries, a relatively low internal resistance, and a lowself-discharge rate when not in use. Lithium-class batteries may be usedas primary, or non-rechargeable, batteries and secondary, orrechargeable, batteries.

Lithium-class batteries may be used in stationary and portable devices,such as those encountered in the consumer electronic, automobile,healthcare, and aerospace industries. In the automotive industry,lithium-based batteries may be suitable for electric-based vehicles,such as hybrid electric vehicles (“HEVs”), battery electric vehicles(“BEVs”), plug-in HEVs, and extended-range electric vehicles (“EREVs”).The ability of lithium batteries to undergo repeated power cycling overtheir useful lifetimes makes them an attractive and dependable powersource.

SUMMARY

According to aspects of the present disclosure, a method includespreparing a ternary mixture including an electrolyte portion, a matrixprecursor portion, and a self-healing portion, forming a self-healinggel-electrolyte membrane by initiating polymerization of the gel-formingprecursor and the gel-forming initiator to thereby form a polymermatrix, and disposing the self-healing gel-electrolyte membrane betweenan anode and a cathode. The self-healing portion includes a self-healingprecursor that is flowable and a self-healing initiator. The matrixprecursor portion includes a gel-forming precursor and a gel-forminginitiator. The electrolyte portion and the self-healing portion aredisposed substantially throughout the polymer matrix. The polymer matrixincludes a plurality of gel-forming active sites.

According to further aspects of the present disclosure, the self-healingprecursor is a cyclic ether and the self-healing initiator is alithium-containing compound.

According to further aspects of the present disclosure, the gel-formingprecursor is a branched acrylate and the gel-forming initiator is a UVinitiator.

According to further aspects of the present disclosure, the electrolyteportion is an organic electrolyte.

According to further aspects of the present disclosure, the self-healingprecursor is a cyclic ether having the formula CH₂OC₂H₄O and theself-healing initiator is lithium bis(fluorosulfonyl)imide (“LiFSI”).

According to further aspects of the present disclosure, the gel-formingprecursor is a branched acrylate having a functional moiety selectedfrom the group consisting of a carboxylic acid and an ester and thegel-forming initiator is 1,1-diphenylmethanone.

According to further aspects of the present disclosure, the electrolyteportion includes a lithium-containing salt selected from the groupconsisting of lithium perchlorate (LiClO₄), lithium hexafluoroarsenate(V) (LiAsF₆), lithium hexafluorophosphate (LiPF₆), lithiumtetrafluoroborate (LiBF₄), lithium bis(trifluoromethanesulfonyl)imide(LiC₂F₆NO₄S₂) (“LiTFSI”), and combinations thereof.

According to further aspects of the present disclosure, the methodfurther includes applying the ternary mixture to a substrate prior toforming the self-healing gel-electrolyte membrane.

According to further aspects of the present disclosure, the substrate isselected from the group consisting of the anode, the cathode, and aseparator.

According to further aspects of the present disclosure, the methodfurther includes filling, in response to a fracture formed in thepolymer matrix contacting the self-healing precursor, at least a portionof the fracture with the self-healing precursor, and polymerizing, inresponse to the self-healing precursor contacting the self-healinginitiator, the self-healing precursor to thereby inhibit propagation ofthe fracture through the self-healing gel-electrolyte membrane.

According to further aspects of the present disclosure, the self-healingportion is present in the ternary mixture in an amount of two parts byweight based on ten parts by weight of the ternary mixture, the matrixprecursor portion is present in the ternary mixture in an amount of twoparts by weight based on ten parts by weight of the ternary mixture, andthe electrolyte is present in the ternary mixture in an amount of sixparts by weight based on ten parts by weight of the ternary mixture.

According to further aspects of the present disclosure, at least one ofthe anode and the cathode includes a binder, the binder formed from abinary mixture including the matrix precursor portion and theself-healing portion, the binder binding an active material therein, theactive material being selected from the group consisting oflithium-containing materials and sulfur-containing materials.

According to further aspects of the present disclosure, at least one ofthe anode and the cathode is an active-lithium electrode and theself-healing gel-electrolyte membrane is a coating on the at least oneof the anode and the cathode to thereby prevent precipitation oftransition metals on the active-lithium electrode.

According to further aspects of the present disclosure, an activematerial of at least one of the anode and the cathode include sulfur andthe self-healing gel-electrolyte membrane prevents electrical shortsbetween the anode and the cathode.

According to further aspects of the present disclosure, an activematerial of at least one of the anode and the cathode include sulfur andthe self-healing gel-electrolyte membrane prevents polysulfide shuttlingwithout lithium nitrate present between the anode and the cathode.

According to further aspects of the present disclosure, the anode isformed from a mixture including silicon particles, the self-healingportion and the matrix precursor portion and wherein, afterpolymerization of the matrix precursor portion, the silicon particlesare encapsulated within the polymer matrix.

According to aspects of the present disclosure, a battery cell includesan anode, a cathode, and a self-healing membrane disposed between theanode and the cathode. The self-healing membrane is prepared by aprocess including preparing a ternary mixture including an electrolyteportion, a matrix precursor portion, and a self-healing portion andforming a self-healing gel-electrolyte membrane by initiatingpolymerization of the gel-forming precursor and the gel-forminginitiator to thereby form a polymer matrix. The self-healing portionincludes a self-healing precursor that is flowable and a self-healinginitiator. The matrix precursor portion includes a gel-forming precursorand a gel-forming initiator. The electrolyte portion and theself-healing portion are disposed substantially throughout the polymermatrix. The polymer matrix includes a plurality of gel-forming activesites. According to further aspects of the present disclosure, theprocess further includes applying the ternary mixture to a substrateprior to forming the self-healing gel-electrolyte membrane.

According to further aspects of the present disclosure, the self-healingprecursor, in response to contact with a fracture in the self-healinggel-electrolyte membrane, fills at least a portion of the fracture, andthe self-healing precursor, in response to contact with the self-healinginitiator, polymerizes to thereby inhibit propagation of the fracture.

According to further aspects of the present disclosure, the self-healingprecursor is a cyclic ether and the self-healing initiator is alithium-containing compound.

According to aspects of the present disclosure, a method includespreparing a mixture including an electrolyte portion and a matrixprecursor portion, forming an electrolyte membrane by initiatingpolymerization of the gel-forming precursor and the gel-forminginitiator to thereby form a polymer matrix, and disposing theelectrolyte membrane between an anode and a cathode. The matrixprecursor portion includes a gel-forming precursor and a gel-forminginitiator. The electrolyte portion is disposed substantially throughoutthe polymer matrix.

According to further aspects of the present disclosure, the gel-forminginitiator is a thermal initiator.

According to further aspects of the present disclosure, the thermalinitiator is selected from the group consisting ofazobisisobutyronitrile, 1,1′-azobis(cyclohexanecarbonitrile), benzoylperoxide, di-tert-butyl peroxide.

According to further aspects of the present disclosure, the thermalinitiator is azobisisobutyronitrile.

According to further aspects of the present disclosure, the gel-forminginitiator is a UV initiator.

According to further aspects of the present disclosure, the UV initiatoris a phenone compound.

According to further aspects of the present disclosure, the UV initiatoris selected from the group consisting of 1,1-diphenylmethanone,4,4′-dihydroxybenzophenone, acetophenone, anisoin, benzil, benzoin,2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone, camphorquinone,4′-ethoxyacetophenone, methybenzoylformate,2-methyl-4′-(methylthio)-2-morpholinopropiophenone, andthioxanthen-9-one.

According to further aspects of the present disclosure, the UV initiatoris 1,1-diphenylmethanone.

According to further aspects of the present disclosure, the gel-forminginitiator is an electron-beam initiator.

According to further aspects of the present disclosure, theelectron-beam initiator is a diaryliodonium salt or a triarylsulfoniumsalt.

According to further aspects of the present disclosure, thediaryliodonium salt or the triarylsulfonium salt include a counter ionselected from the group consisting of hexafluoroarsenate,hexafluoroantimonate, hexafluorophosphate, and tetrafluoroborate.

According to further aspects of the present disclosure, theelectron-beam initiator is diaryliodonium hexafluoroantimonate.

According to further aspects of the present disclosure, the methodfurther includes applying the mixture to a battery component using atleast one of slurry coating, spray coating, or dip coating.

According to further aspects of the present disclosure, the methodfurther includes applying the mixture to a battery component wherein themixture is applied to a battery component using dip coating, the mixturecoating surfaces of the battery component, and wherein a portion of themixture is polymerized, the portion corresponding to less than all ofthe surfaces.

According to further aspects of the present disclosure, the gel-formingprecursor is a branched acrylate.

According to further aspects of the present disclosure, the branchedacrylate includes a functional moiety selected from the group consistingof a carboxylic acid and an ester.

According to further aspects of the present disclosure, the electrolyteportion includes a lithium-containing salt selected from the groupconsisting of lithium perchlorate (LiClO₄), lithium hexafluoroarsenate(V) (LiAsF₆), lithium hexafluorophosphate (LiPF₆), lithiumtetrafluoroborate (LiBF₄), lithium bis(trifluoromethanesulfonyl)imide(LiC₂F₆NO₄S₂) (“LiTFSI”), and combinations thereof.

According to further aspects of the present disclosure, the methodfurther includes applying the mixture to a substrate prior to formingthe electrolyte membrane.

According to further aspects of the present disclosure, the substrate isselected from the group consisting of the anode, the cathode, and aseparator.

According to aspects of the present disclosure, a battery cell includesan anode, a cathode, and an electrolyte membrane therebetween. Theelectrolyte membrane is formed from a mixture including a matrixprecursor portion and an electrolyte portion.

According to further aspects of the present disclosure, the electrolytemembrane is a coating on a battery component.

According to further aspects of the present disclosure, mixture ispolymerized after being applied to the battery component.

According to further aspects of the present disclosure, the batterycomponent is at least one of the anode and a separator.

According to further aspects of the present disclosure, the batterycomponent is the anode.

According to further aspects of the present disclosure, the anode is alithium-metal anode.

According to further aspects of the present disclosure, the batterycomponent is a separator.

According to further aspects of the present disclosure, the electrolytemembrane is a self-healing separator.

According to further aspects of the present disclosure, the mixturefurther includes a self-healing portion, the self-healing portionincludes a self-healing precursor and a self-healing initiator, andwherein the self-healing precursor is flowable.

According to further aspects of the present disclosure, the self-healingprecursor is configured to, in response to contact with a fracture inthe electrolyte membrane, fill at least a portion of the fracture, andthe self-healing precursor is configured to, in response to contact withthe self-healing initiator, polymerize to thereby inhibit propagation ofthe fracture through the electrolyte membrane.

According to further aspects of the present disclosure, the self-healingprecursor is a cyclic ether and the self-healing initiator is alithium-containing compound.

According to further aspects of the present disclosure, the matrixprecursor portion is free of solvent.

According to further aspects of the present disclosure, the matrixprecursor portion includes a gel-forming precursor configured to form apolymer matrix and a gel-forming initiator configured to initiatepolymerization of the gel-forming precursor.

According to further aspects of the present disclosure, the gel-formingprecursor is a branched acrylate.

According to further aspects of the present disclosure, the gel-forminginitiator is a thermal initiator.

According to further aspects of the present disclosure, the thermalinitiator is selected from the group consisting ofazobisisobutyronitrile, 1,1′-azobis(cyclohexanecarbonitrile), benzoylperoxide, di-tert-butyl peroxide.

According to further aspects of the present disclosure, the gel-forminginitiator is a UV initiator.

According to further aspects of the present disclosure, the UV initiatoris selected from the group consisting of 1,1-diphenylmethanone,4,4′-dihydroxybenzophenone, acetophenone, anisoin, benzil, benzoin,2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone, camphorquinone,4′-ethoxyacetophenone, methybenzoylformate,2-methyl-4′-(methylthio)-2-morpholinopropiophenone, thioxanthen-9-one.

According to further aspects of the present disclosure, the gel-forminginitiator is an electron-beam initiator.

According to further aspects of the present disclosure, theelectron-beam initiator is selected from the group consisting ofdiaryliodonium salts and triarylsulfonium salts.

The above features and advantages and other features and advantages ofthe present disclosure are readily apparent from the following detaileddescription of the best modes for carrying out the disclosure when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are illustrative and not intended to limit the subjectmatter defined by the claims. Exemplary aspects are discussed in thefollowing detailed description and shown in the accompanying drawings inwhich:

FIG. 1 illustrates a schematic battery cell having a self-healinggel-electrolyte membrane, according to aspects of the presentdisclosure;

FIG. 2 illustrates a schematic method according to aspects of thepresent disclosure;

FIG. 3 illustrates a schematic plot of total capacitance by cycle numberfor an example battery cell;

FIG. 4 illustrates a schematic plot of specific capacity and coulombicefficiency by cycle number for another example battery cell;

FIG. 5 illustrates a schematic battery cell, according to furtheraspects of the present disclosure; and

FIG. 6 illustrates a schematic method according to further aspects ofthe present disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates a schematic battery cell 100. The battery cell 100includes a cathode 102, an anode 104, and an electrolyte membrane 106disposed between the cathode 102 and the anode 104. In some aspects, theanode 104 is a lithium-class anode. For example, active material of theanode 104 may include intercalated lithium. In some aspects, the activematerial of the anode 104 is a lithium-sulfide anode compound, such asthose provided by U.S. Patent Publication No. 2015/0221935 to Zhou andU.S. Patent Publication No. 2015/0162583 to Dadheech, each of which ishereby incorporated by reference in its entirety. The active material ofthe cathode 102 is selected to facilitate an electrochemical reaction ofthe anode 104. In some aspects, the active material of the cathode 102is copper. In some aspects, the active material of the cathode 104 is asulfur-containing material.

Beneficially, the electrolyte membrane 106 may improve operable lifetimeof battery packs implementing the battery cells 100 by inhibitingdendrite formation in lithium-metal batteries and polysulfide shuttlingin lithium-sulfur batteries. Further, the electrolyte membrane 106 asdisclosed herein is compatible with most electrode active materials andliquid phase electrolytes. Moreover, the electrolyte membrane 106disclosed herein may reduce manufacturing costs of the battery cell 100by avoiding costs of metal catalyst initiators such as rare metalcatalysts. Additionally, the electrolyte membrane 106 disclosed hereinmay be implemented as a binder for the anode 104 and cathode 102 inlithium batteries. What is more, the electrolyte membrane 106 may alsobe implemented as a coating for active electrodes such as the anode 104to prevent transition-metal deposition when using a cathode 102 based ontransition-metal oxides. Moreover, the electrolyte membrane 106 could beused as a coating in power cells to prevent self-discharge due to thereaction or oxidation of the electroactive material, such as activelithium titanate (“LTO”), which may be used as an anode material withthe electrolyte. The electrolyte membrane 106 may also be used to form ashell around silicon particles used in high-energy-density lithiumbatteries that use silicon as an active material for the anode 104.

The electrolyte membrane 106 is formed from a binary mixture thatincludes an electrolyte portion and a matrix precursor portion. Theelectrolyte portion is configured to allow for ionic transfer throughthe electrolyte membrane 106. In some aspects, the electrolyte portionis an organic electrolyte, such as a lithium-containing salt, in anorganic solvent. In some aspects, the lithium-containing salt isselected from the group consisting of lithiumbis(trifluoromethanesulfonyl)imide (LiC₂F₆NO₄S₂) (“LiTFSI”), lithiumperchlorate (LiClO₄), lithium hexafluoroarsenate (LiAsF₆), lithiumtetrafluoroborate (LiBF₄), lithium hexafluorophosphate (LiPF₆),combinations thereof, and the like. In some aspects, the organic solventor cosolvent is a carbonate-group solvent. For example, the organicsolvent or cosolvent may be ethylene carbonate ((CH₂O)₂CO), propylenecarbonate (CH₃C₂H₃O₂CO), diethyl carbonate (OC(OCH₂CH₃)₂), combinationsthereof, and the like.

The matrix precursor portion is configured to form a polymer matrix thatdefines a structure of the self-healing gel-electrolyte membrane 106.The matrix precursor portion includes a gel-forming precursor and agel-forming initiator. Beneficially, in some aspects, the matrixprecursor portion is free of solvent such that formation of the polymermatrix defining the electrolyte membrane 106 occurs without solventevaporation.

The gel-forming precursor is configured to form the polymer of thepolymer matrix. In some aspects, the gel-forming precursor is a branchedprecursor. In some aspects, the gel-forming precursor is a branchedacrylate having a functional moiety selected from the group consistingof a carboxylic acid and an ester.

The gel-forming initiator is configured to initiate polymerization ofthe gel-forming precursor in response to reaching predetermined physicalconditions. In some aspects, the gel-forming initiator is a UV initiatorthat initiates polymerization of the gel-forming precursor in responseto being exposed to UV light. For example, the UV initiator may be aphenone compound. In some aspects, the UV initiator is selected from thegroup consisting of 1,1-diphenylmethanone (“benzophenone”),4,4′-dihydroxybenzophenone, acetophenone, anisoin, benzil, benzoin,2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone, camphorquinone,4′-ethoxyacetophenone, methybenzoylformate,2-methyl-4′-(methylthio)-2-morpholinopropiophenone, thioxanthen-9-one,combinations thereof, and the like. Beneficially, UV initiators providefor polymerization of the gel-forming precursor that may be quicklyinitiated or halted.

In some aspects, the gel-forming initiator is an electron-beam initiatorthat initiates polymerization of the gel-forming precursor in responseto being exposed to an electron beam. For example, the electron-beaminitiator may be selected from the group consisting of diaryliodoniumsalts and triarylsulfonium salts. In some aspects, the diaryliodoniumsalts and triarylsulfonium salts include counter ions ofhexafluoroarsenate, hexafluoroantimonate, hexafluorophosphate,tetrafluoroborate, combinations thereof, and the like.

In some aspects, the gel-forming initiator is a thermal initiator thatinitiates polymerization of the gel-forming precursor in response tobeing exposed to elevated temperatures. For example, the thermalinitiator may be selected from the group consisting ofazobisisobutyronitrile, 1,1′-azobis(cyclohexanecarbonitrile), benzoylperoxide, di-tert-butyl peroxide, combinations thereof, and the like.Beneficially, thermal initiators may be used to provide forpolymerization of the gel-forming precursor when disposed inside of aproduct or when a view of the gel-forming precursor is obscured.

In some aspects, the electrolyte membrane 106 is a self-healinggel-electrolyte membrane. Beneficially, the self-healing gel-electrolytemembrane may additionally inhibit thermal runaway events resulting from,for example, a puncture to the battery cell 100. The self-healinggel-electrolyte membrane is formed from a ternary mixture that includesthe electrolyte portion, the matrix precursor portion, and aself-healing portion.

The self-healing portion includes a self-healing precursor and aself-healing initiator. The self-healing portion is dispersed in theself-healing gel-electrolyte membrane such that a fracture in theself-healing gel-electrolyte membrane will contact the self-healingprecursor and the self-healing initiator. The self-healing precursor andthe self-healing initiator are selected to inhibit propagation of afracture through the polymer matrix after contact between theself-healing precursor and the self-healing initiator.

The self-healing precursor and/or the self-healing initiator aremaintained within deposits throughout the polymer matrix. In someaspects, the deposits are within well-defined containment structuressuch as microspheres or tubular structures having a relatively uniformsize distribution. In some aspects, the deposits of the self-healingprecursor and/or the self-healing initiator are formed because theself-healing precursor and/or self-healing initiator are containedwithin well-defined containment structures formed by a separateencapsulant. In some aspects, the deposits of the self-healing precursorand/or the self-healing initiator are formed because the self-healingprecursor and/or the self-healing initiator are immiscible within theternary mixture.

As a fracture propagates through the polymer matrix, the fracture willcontact the self-healing precursor. The self-healing precursor isconfigured to be flowable such that, in response to contact with thefracture in the self-healing gel-electrolyte membrane 106, theself-healing precursor fills at least a portion of the fracture.Further, the self-healing precursor is configured to polymerize inresponse to contact with the self-healing initiator to thereby inhibitpropagation of the fracture. The distribution and amount of self-healingprecursor within the polymer matrix are selected to inhibit fracturesfrom propagating further than a certain average distance. For example,an increased load of the self-healing precursor reduces the statisticaldistance a fracture may propagate through the self-healinggel-electrolyte membrane 106 before the fracture would contact a depositof the self-healing precursor.

In some aspects, the self-healing portion is substantially uniformlydistributed throughout the polymer matrix. In some aspects, theself-healing portion is loaded more heavily toward the edges of thepolymer matrix that face the cathode 102 or the anode 104. Beneficially,such a non-uniform distribution may inhibit propagation of fracturesfrom the edges of the self-healing gel-electrolyte membrane 106 whilereducing the overall amount of self-healing portion required to inhibitfracture propagation.

In some aspects, the self-healing precursor is selected such that theself-healing precursor and polymers formed therefrom may attach togel-forming active sites within the polymer matrix. Beneficially, suchan attachment may increase the strength of the self-healed portion andprovide greater resistance against further propagation.

In some aspects, the self-healing precursor is selected to polymerizethrough a cationic ring-opening polymerization process. In some aspects,the self-healing precursor is a cyclic molecule capable ofpolymerization. In some aspects, the self-healing precursor is a cyclicether. In some aspects, the self-healing precursor is cyclic etherhaving the formula CH₂OC₂H₄O.

In some aspects, the self-healing initiator is a lithium-containingcompound. In some aspects, the self-healing initiator is flowable suchthat, upon contact with the fracture, the self-healing initiator fillsat least a portion of the fracture. Beneficially, a flowableself-healing initiator may increase the rate of polymerization throughincreased mixing with the self-healing precursor. In some aspects, theself-healing initiator is a lithium imide compound. In some aspects, theself-healing initiator is lithium bis(fluorosulfonyl)imide. In someaspects, the self-healing precursor is contained within an inertmicrocapsule and the self-healing initiator is a component within theelectrolyte portion.

In some aspects, the battery cell 100 further includes an anode-sidecurrent collector 108A and a cathode-side current collector 108C. Theanode-side current collector 108A may be disposed adjacent the anode 104and may be configured to balance current distribution and increasecharge transfer across the anode 104. The cathode-side current collector108C may be disposed adjacent the cathode 102 and may be configured tobalance current distribution and increase charge transfer across thecathode 102. An external circuit 110 may electrically couple theanode-side current collector 108A to the cathode-side current collector108C.

The external circuit 110 may allow current to flow between theanode-side current collector 108A and the cathode-side current collector108C.

FIG. 5 illustrates a schematic battery cell 500 including the cathode102, the anode 104, the electrolyte membrane 106, and a separator 502.The separator 502 is an electrically insulating and ion-permeablemembrane disposed between the cathode 102 and the anode 104. In someaspects, the separator 502 is a polymer film such as polyethylene,polypropylene, poly(tetrafluoroethylene), polyvinyl chloride,combinations thereof, and the like. The separator 502 may furtherinclude inorganic fillers such as titanium dioxide, silicon dioxide,aluminum oxides, zeolite, lithium niobate, lithium tantalate,combinations thereof, and the like.

The separator 502 is disposed between the cathode 102 and the anode 104.The electrolyte membrane 106 is disposed between the separator 502 andthe anode 104, while another electrolyte 504 is disposed between theseparator 502 and the cathode 102. The electrolyte 504 may be a liquid,gel, or solid electrolyte. In some aspects, the electrolyte 504 is asecond electrolyte membrane 106. In some aspects, the membrane 106 isformed directly on an anode-side of the separator 502 as a coating andis then brought into contact with the anode 102. In some aspects, themembrane 106 is formed directly on the anode 104 as a coating and isthen brought into contact with the separator 502. In some aspects, themembrane 106 is formed in situ between and contacting both the anode 104and the separator 502.

In some aspects, the separator 502 is formed from a binary mixtureincluding the matrix precursor portion and the electrolyte portion. Insome aspects, the separator 502 is a self-healing separator 502 formedfrom the ternary mixture including the self-healing portion, the matrixprecursor portion, and the electrolyte portion.

FIG. 6 illustrates a method 600 of providing an electrolyte membrane 106for a battery cell 100. The method includes preparing 602 a mixtureincluding the electrolyte portion and the matrix precursor portion,applying 604 the mixture to a substrate, forming 606 the electrolytemembrane 106 on the substrate via polymerization of the matrix precursorportion.

In some aspects, the mixture is in the form of a slurry which is coatedonto the substrate. In some aspects, the mixture is spray coated ontothe substrate. In some aspects, the mixture is contained in a pool, andthe substrate is dip coated by at least partially submerging a surfaceof the substrate into the pool.

Forming 606 the electrolyte membrane 106 may include, for example,polymerization via thermal initiation, UV initiation, electron-beaminitiation, or combinations thereof. Beneficially, while dip-coating ofthe substrate may provide the mixture on multiple surfaces of thesubstrate, thermal, UV, or electron-beam initiation of polymerizationmay be used to selectively polymerize a portion of the mixture (forexample, polymerizing only the mixture on a single face of thesubstrate) while the remaining, unpolymerized portion of the mixture maybe removed. Beneficially, the unpolymerized portion may serve as aprotective layer for the substrate during certain processing procedures.For example, the unpolymerized portion may protect the substrate whenexposed to the atmosphere.

Referring now to FIG. 2, a method 200 of providing a self-healinggel-electrolyte membrane for a battery cell 100 is shown. The method 200includes preparing 202 a ternary mixture including the electrolyteportion, the matrix precursor portion, and the self-healing portion,forming 204 the self-healing gel-electrolyte membrane by initiatingpolymerization of the gel-forming precursor and the gel-forminginitiator, and disposing 206 the self-healing gel-electrolyte membranebetween the cathode 102 and the anode 104.

In some aspects, initiating polymerization of the gel-forming precursorand the gel-forming initiator includes at least one of thermalinitiation, UV initiation, electron-beam initiation, or combinationsthereof. Beneficially, use of thermal, UV, or electron-beam initiationprovides for in situ formation of the membrane 106. Such in situformation, as well as the matrix precursor portion and formation of thepolymer matrix being free of solvent optimizes performance oflithium-metal anodes by obviating surface modification of thelithium-metal anode prior to contact with and/or formation of themembrane 106.

The self-healing portion includes a self-healing precursor that isflowable and a self-healing initiator. The matrix precursor portionincludes a gel-forming precursor and a gel-forming initiator. Initiatingpolymerization of the gel-forming precursor and the gel-forminginitiator thereby forms a polymer matrix. The electrolyte portion andthe self-healing portion are substantially throughout the polymermatrix. The polymer matrix includes a plurality of gel-forming activesites.

In some aspects, the ternary mixture is prepared by mixing theelectrolyte portion, the matrix precursor portion, and the self-healingportion together in solution. In some aspects, the self-healing portionis added to a mixture of the electrolyte portion and the matrixprecursor portion immediately prior to initiating curing of the matrixprecursor portion to inhibit polymerization of the self-healingprecursor. In some aspects, the electrolyte portion, the matrixprecursor portion, and one of the self-healing precursor and theself-healing initiator are mixed together while the other of theself-healing precursor and the self-healing initiator is added to themixture immediately prior to initiating curing of the matrix precursorportion to inhibit polymerization of the self-healing precursor.

The ternary mixture may be applied to a substrate prior to forming theself-healing gel-electrolyte membrane 106. In some aspects, thesubstrate is a removable backer. For example, the ternary mixture may bedeposited onto the removable backer for curing of the polymer matrix.After polymerization of the matrix precursor has proceeded to apredetermined extent that the self-healing gel-electrolyte membrane 106is freestanding and manipulatable without damage, the removable backeris separated from the self-healing gel-electrolyte membrane 106. Theself-healing gel-electrolyte membrane 106 may then be placed between theanode and the cathode of the battery cell. Placement of the self-healinggel-electrolyte membrane 106 may be achieved through abutting theself-healing gel-electrolyte membrane 106 with one or more of the anode104 or the cathode 102.

In some aspects, the substrate is selected from the group consisting ofthe anode 104, the cathode 102, and the separator. For example, theternary mixture may be deposited onto the cathode 102 for curing of thepolymer matrix. In some aspects, another battery component, such as theanode 104 or the separator, is applied to the ternary mixture oppositethe cathode prior to curing of the polymer matrix. In some aspects,another battery component, such as the anode or the separator, isapplied to the ternary mixture after polymerization of the polymermatrix has proceeded to a predetermined extent that the self-healinggel-electrolyte membrane 106 is freestanding and manipulatable withoutdamage.

In some aspects, at least one of the anode 104 and the cathode 102includes a binder which binds an active material therein. The binder maybe formed from a binary mixture including the matrix precursor portionand the self-healing portion. In some aspects, the active material isselected from the group consisting of lithium-containing materials andsulfur-containing materials.

In some aspects, at least one of the anode 104 and the cathode 102 is anactive-lithium electrode and the self-healing gel-electrolyte membraneis a coating on the at least one of the anode 104 and the cathode 102 tothereby prevent precipitation of transition metals on the active-lithiumelectrode.

In some aspects, the active material of at least one of the anode 104and the cathode 102 includes sulfur and the self-healing gel-electrolytemembrane prevents electrical shorts between the anode 104 and thecathode 102.

In some aspects, the active material of at least one of the anode 104and the cathode 102 include sulfur and the self-healing gel-electrolytemembrane prevents polysulfide shuttling without lithium nitrate presentbetween the anode 104 and the cathode 102.

In some aspects, the anode 104 is formed from a mixture includingsilicon particles, the self-healing portion, and the matrix precursorportion. After polymerization of the matrix precursor portion for theanode 104, the silicon particles are encapsulated within the polymermatrix. Beneficially, the self-healing portion within the polymer matrixprevents damage to the polymer matrix from thermal expansion andcontraction of the silicon particles.

For purposes of the present detailed description, the singular includesthe plural and vice versa (unless specifically disclaimed); the words“and” and “or” shall be both conjunctive and disjunctive; the word “all”means “any and all”; the word “any” means “any and all”; and the word“including” means “including without limitation.” Additionally, thesingular terms “a,” “an,” and “the” include plural referents unlesscontext clearly indicates otherwise.

While the best modes for carrying out the disclosure have been describedin detail, those familiar with the art to which this disclosure relateswill recognize various alternative designs and embodiments forpracticing the disclosure within the scope of the appended claims.

EXAMPLES Example 1

A self-healing gel-electrolyte membrane is formed from a ternary mixtureof an electrolyte portion, a matrix precursor portion, and aself-healing portion. The self-healing portion includes a self-healingprecursor that is a cyclic ether having the formula CH₂OC₂H₄O and aself-healing initiator that is lithium bis(fluorosulfonyl)imide. Thematrix precursor portion includes a gel-forming precursor of a branchedacrylate having a carboxylic acid as the functional moiety and agel-forming initiator of 1,1-diphenylmethanone. The electrolyte portionis an organic electrolyte including lithium hexafluorophosphate in acosolvent combination of ethylene carbonate and dimethyl carbonate, theethylene carbonate being 50% by volume on a basis of the cosolvents andthe dimethyl carbonate being 50% by volume on a basis of the cosolvents.The electrolyte portion is 60 percent by weight on a basis of the totalweight of the ternary mixture. The matrix precursor portion is 20percent by weight on a basis of the total weight of the ternary mixture.The self-healing portion is 20 percent by weight on a basis of the totalweight of the ternary mixture.

The battery cell is a half-cell configuration of a lithium anode, aliquid electrolyte layer, a self-healing gel-electrolyte membrane, and acopper cathode. The lithium anode is adjacent the liquid electrolytelayer. The liquid electrolyte layer is disposed between the lithiumanode and the self-healing gel-electrolyte membrane. The self-healinggel-electrolyte membrane is disposed between the liquid electrolytelayer and the copper cathode. The composition of the liquid electrolytelayer is 1 molar lithium hexafluorophosphate in ethylene carbonate anddimethyl carbonate, the ethylene carbonate being 50% by volume on abasis of the cosolvents and the dimethyl carbonate being 50% by volumeon a basis of the cosolvents.

After assembly, the battery cell is tested for total capacity overcharge-discharge cycles. The charge cycle is run to 1 mAh/cm² at a rateof 0.25 mA/cm² and the discharge cycle is run at a rate of 0.25 mA/cm².FIG. 3 is a plot of total capacity for each cycle obtained. As can beseen, the total capacity has an initial coulombic efficiency of lessthan 96%. As the cycles increase, the coulombic efficiency increases togreater than 99%.

Example 2

A self-healing gel-electrolyte membrane is formed from a ternary mixtureof an electrolyte portion, a matrix precursor portion, and aself-healing portion. The self-healing portion includes a self-healingprecursor that is a cyclic ether having the formula CH₂OC₂H₄O and aself-healing initiator that is lithium bis(fluorosulfonyl)imide. Thematrix precursor portion includes a gel-forming precursor of a branchedacrylate having a carboxylic acid as the functional moiety and agel-forming initiator of 1,1-diphenylmethanone. The electrolyte portionis an organic electrolyte including lithium hexafluorophosphate in acosolvent combination of ethylene carbonate and dimethyl carbonate, theethylene carbonate being 50% by volume on a basis of the cosolvents andthe dimethyl carbonate being 50% by volume on a basis of the cosolvents.The electrolyte portion is 60 percent by weight on a basis of the totalweight of the ternary mixture. The matrix precursor portion is 20percent by weight on a basis of the total weight of the ternary mixture.The self-healing portion is 20 percent by weight on a basis of the totalweight of the ternary mixture.

The battery cell is a half-cell configuration of a lithium anode, aself-healing gel-electrolyte membrane, a liquid electrolyte layer, and asulfur-containing cathode. The lithium anode is adjacent theself-healing gel-electrolyte membrane. The self-healing gel-electrolytemembrane is disposed between the lithium anode and the liquidelectrolyte layer. The liquid electrolyte layer is disposed between theself-healing gel-electrolyte membrane and the copper cathode. Thecomposition of the liquid electrolyte layer is 1 molar LiTFSI in1,3-dioxolane (“DOL”) and 1,2-dimethoxyethane (“DME”), the DOL being 50%by volume on a basis of the cosolvents and the DME being 50% by volumeon a basis of the cosolvents. Notably, the battery cell of this exampledoes not include lithium nitrate (LiNO₃). Beneficially, the self-healinggel-electrolyte membrane inhibits overcharge conditions caused bypolysulfide redox shutting without additional inhibitors such as lithiumnitrate. For example, a similar lithium-sulfur battery lacking both aself-healing gel-electrolyte membrane and lithium nitrate suffers frompolysulfide shuttling and overcharge until the electrolyte dries outwhile the example battery cell continued to function and did not showeffects of polysulfide shuttling.

After assembly, the battery cell is tested for total capacity overcharge-discharge cycles. The charge cycle is run to 1 mAh/cm² at a rateof 0.25 mA/cm² and the discharge cycle is run at a rate of 0.25 mA/cm².FIG. 4 is a plot of specific capacity and coulombic efficiency by cyclenumber. As can be seen, a coulombic efficiency of greater than 99% wasreached after a few cycles with a specific capacity of about 900 mAh/g.

What is claimed is:
 1. A method comprising: preparing a mixtureincluding an electrolyte portion and a matrix precursor portion, thematrix precursor portion including a gel-forming precursor and agel-forming initiator; forming an electrolyte membrane by initiatingpolymerization of the gel-forming precursor and the gel-forminginitiator to thereby form a polymer matrix, the electrolyte portiondisposed substantially throughout the polymer matrix; and disposing theelectrolyte membrane between an anode and a cathode.
 2. The method ofclaim 1, wherein the gel-forming initiator is a thermal initiator. 3.The method of claim 2, wherein the thermal initiator is selected fromthe group consisting of azobisisobutyronitrile,1,1′-azobis(cyclohexanecarbonitrile), benzoyl peroxide, di-tert-butylperoxide.
 4. The method of claim 2, wherein the thermal initiator isazobisisobutyronitrile.
 5. The method of claim 1, wherein thegel-forming initiator is a UV initiator.
 6. The method of claim 5,wherein the UV initiator is a phenone compound.
 7. The method of claim5, wherein the UV initiator is selected from the group consisting of1,1-diphenylmethanone, 4,4′-dihydroxybenzophenone, acetophenone,anisoin, benzil, benzoin,2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone, camphorquinone,4′-ethoxyacetophenone, methybenzoylformate,2-methyl-4′-(methylthio)-2-morpholinopropiophenone, andthioxanthen-9-one.
 8. The method of claim 5, wherein the UV initiator is1,1-diphenylmethanone.
 9. The method of claim 1, wherein the gel-forminginitiator is an electron-beam initiator.
 10. The method of claim 9,wherein the electron-beam initiator is a diaryliodonium salt or atriarylsulfonium salt.
 11. The method of claim 10, wherein thediaryliodonium salt or the triarylsulfonium salt include a counter ionselected from the group consisting of hexafluoroarsenate,hexafluoroantimonate, hexafluorophosphate, and tetrafluoroborate. 12.The method of claim 9, wherein the electron-beam initiator isdiaryliodonium hexafluoroantimonate.
 13. The method of claim 1, furthercomprising applying the mixture to a battery component using at leastone of slurry coating, spray coating, or dip coating.
 14. The method ofclaim 1, further comprising applying the mixture to a battery componentwherein the mixture is applied to a battery component using dip coating,the mixture coating surfaces of the battery component, and wherein aportion of the mixture is polymerized, the portion corresponding to lessthan all of the surfaces.
 15. The method of claim 1, wherein thegel-forming precursor is a branched acrylate.
 16. The method of claim15, wherein the branched acrylate includes a functional moiety selectedfrom the group consisting of a carboxylic acid and an ester.
 17. Themethod of claim 15, wherein the electrolyte portion includes alithium-containing salt selected from the group consisting of lithiumperchlorate (LiClO₄), lithium hexafluoroarsenate (V) (LiAsF₆), lithiumhexafluorophosphate (LiPF₆), lithium tetrafluoroborate (LiBF₄), lithiumbis(trifluoromethanesulfonyl)imide (LiC₂F₆NO₄S₂) (“LiTFSI”), andcombinations thereof.
 18. The method of claim 1, further comprisingapplying the mixture to a substrate prior to forming the electrolytemembrane.
 19. The method of claim 18, wherein the substrate is selectedfrom the group consisting of the anode, the cathode, and a separator.